1. Field of the Invention
The present invention relates to a waterproof connector and a method of manufacturing the same and, more particularly, to a waterproof connector adapted to interrupt entry of water into a covered electric wire so as to prevent water from entering into the connector by way of a core wire thereof and a method of manufacturing the same.
2. Description of Relevant Art
In FIGS. 1A and 1B and FIG. 2, there is shown a conventional example of a waterproof structure for an electric wire drawout portion of a waterproof connector (see Japanese Utility Model Application Laid-Open Publication No. 50-54591).
The waterproof connector shown in FIGS. 1A and 1B is of a structure wherein a covered electric wire 7 is clamped by two split upper and lower rubber plugs 30 (see FIG. 1A) and the rubber plugs 30 are forcedly inserted into a concavity portion 32 of a connector housing 2 as in FIG. 1B in a state where the covered electric wire 7 has been fitted into grooves 31 of the rubber plugs 30.
Also, a waterproof connector 1a shown in FIG. 2 is of a structure wherein each covered electric wire 7 is covered by corresponding individual rubber plugs 30a and respective end portions of these rubber plugs 30a are caulked (33a) to a terminal 33 and, in this state, are forcedly inserted into a connector housing 2.
In any one of these waterproof connectors 1 and 1a, as shown in FIG. 2, within the interior of the connector housing 2, a core wire 7a of the covered electric wire 7 is caulked (33b) to the terminal 33 and this terminal 33 is retained by a retaining portion 34.
Each of the waterproof connectors having the above-described structures involves therein the problem that although an outer periphery of the covered electric wire 7 is sealed by the rubber plugs 30 (or 30a), water cannot be prevented from advancing along the core wire 7a and entering into the interior of the connector housing 2.
Generally, in the case of a covered electric wire, ordinarily, it does not happen that water enters into the interior of a core wire thereof. However, for example, in a case where the covered electric wire 7 connected to the waterproof connector 1 or 1a is earthed as shown in FIG. 3A, or where separate covered electric wires 71 are joined together as shown in FIG. 3B, it sometimes happens that the core wire 7a of the covered electric wire 7 has its covering portion removed to expose the core wire 7a. In such a case, when this exposed core wire 7a is caught by water and as a result the ambient temperature upon the waterproof connector 1 decreases, the pressure in the connector housing 2 also decreases with the result that the connector housing 2 absorbs water. The water which has entered into the interior of the waterproof connector 1 in this way causes a contact to be shortcircuited or corroded.
Further, there are also other problems that the operation of fitting the rubber plugs 30, 30a into the connector housing 2 is troublesome and that, in addition, in the case of the rubber plug 30 in particular, it is necessary to mold the rubber plug 30 by replacing a relevant mold in correspondence with the size of the electric wire and the number of the poles, with the result that the manufacturing cost increases.